Field of the Invention
The present invention relates to a film placed on the input surface of an input device that receives inputs hand-written with a pen, and a pen input device that uses the film.
Description of the Related Art
There exist various kinds of input devices that receive inputs hand-written with a pen, such as a touch-panel display and an input pad. In such input devices, there is a demand for comfortable writing at a time of inputting with a pen. Writing involves various aspects of a writing material, such as slipperiness, softness, and roughness. For example, JP 2003-296008 A (WO 2003/67416 A) discloses a surface material for a pen input device that has improved slipperiness. JP 2013-77135 A discloses a touch-panel sheet material that includes a self-restoring resin layer, and is 0.05 or less in the difference between the static friction coefficient and the kinetic friction coefficient. JP 2013-152714 A (US 2013/0,164,543 A) discloses a touch-sensor overall panel that includes a high-resistance layer made of tin oxide and titanium oxide, and an insulating layer formed on the high-resistance layer and made of a hardening resin or an inorganic oxide, and has a static friction coefficient of 0.2 or smaller and a kinetic friction coefficient of 0.2 or smaller.
The above mentioned surface material disclosed in JP 2003-296008 A has an improved feel of writing that prioritizes slipperiness. However, the feel of writing is not sufficiently comfortable, and there is still a demand for an input surface that realizes writing to be more preferred by users.
The above mentioned sheet material disclosed in JP 2013-77135 A contains a self-restoring resin. Therefore, the soft input surface is liable to irreparable damage or is easily modified. The relationship between the static friction coefficient and the kinetic friction coefficient that provide comfortable writing naturally differs from that in a case where a resin with poor self-restorability is used, but this aspect is not discussed in this literature.
In the above mentioned overall panel disclosed in JP 2013-152714 A, the high-resistance layer is formed by a vapor phase deposition method such as sputtering, and the insulating layer is formed by coating or sputtering as disclosed. However, how the friction coefficients are adjusted is not disclosed at all. If the friction coefficients are controlled by adjusting film forming conditions, product quality will become unstable. Moreover, improvement of operability of a touch sensor is an objective in the literature, and the feel of writing with a writing tool is not fully discussed.